Multiple pipetting apparatus



June 1957 P. J. L. SEQUEIRA MULTIPLE PIPETTING APPARATUS ll Sheets-Sheet1 Filed Aug. 24, 1964 June 27, 1967 J, 1.. SEQUEIRA MULTIPLE PIPETTINGAPPARATUS ll Sheets-Sheet 2 Filed Aug. 24, 1964 flwiwwwww I M a 0 N NY;7 Q HIH HHHHHI MIH HH I IHMW I I I |||\N.IIJ

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MULTIPLE PIPETTING APPARATUS Filed Aug. 24, 1964 ll Sheets-Sheet 3 I ifI:- 55? 14 F/G.3C.

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- iiii i j J L 1% June 1967 P. J. L. SEQUEIRA MULTIPLE PIPETTINGAPPARATUS ll Sheets-Sheet 4 Filed Aug. 24, 1964 uuuwuupu II II II II HII II II II ooeoocoogfi bo wm wt June 27, 1967 R J SEQUEIRA 3,327,535

MULTIPLE PIPETTING APPARATUS l1 Sheets-Sheet 5 Filed Aug. 24, 1964 MNNNKN June 1967 P. J. L. SEQUEIRA 3,327,535

MULTIPLE PIPETTING APPARATUS Filed Aug. 24, 1964 ll Sheets-Sheet 8 June27, 1967 P. J. L. SEQUEIRA 3,327,535

MULTIPLE PIPETTING APPARATUS Filed Aug. 24, 1964 11 Sheets-Sheet 9 June27, 1967 p, J. 1.. SEQUEIRA MULTIPLE PIPETTING APPARATUS ll Sheets-Sheet10 Filed Aug. 24, 1964 FIG. 70.

June 27, 1967 P. J. L. SEQUEIRA 3,327,535 7 MULTIPLE PIPETTING APPARATUSm5 7400/ T K/Q96 L U United States Patent 3,327,535 MULTIPLE FIPETTINGAPPARATUS Peter James Littieiohns Sequeira, 23 Macclesfield Road,Wilmslow, Cheshire, England Filed Aug. 24, 1964, Ser. No. 391,436

Claims priority, application Great Britain, Aug. 24,1963,

33,611/63 14 Claims. (Cl. 73-423) This invention concerns a multiplepipetting apparatus adapted to dispense known proportions from each of aplurality of liquid samples into a plurality of receptacles.

According to the present invention a multiple pipetting apparatuscomprises a base having a support for carrying receptacles arranged inrows extending along the support and in columns extending across thesupport, a member extending across the support and spaced above it, amechanism for producing relative longitudinal movement between thesupport and the member, a line of pipetting tubes mounted on the memberand individually communicating through pipes with respectivepiston-and-cylinder units operated in synchronism to draw liquidsimultaneously into the pipetting tubes or expel liquid simultaneouslyfrom the pipetting tubes, and a device for raising and lowering thepipetting tubes when their lower ends are aligned with a column ofreceptacles. Preferably the units comprise syringes.

Pipetting apparatus in accordance with the invention has the advantagethat it enables routine pipetting such as is necessary for serologicaland biochemical work to be carried out more rapidly than is possiblewhen done manually and with greater average accuracy.

Preferably the support is movable with respect to the base although itis not outside of the scope of the invention to have the support fixedto the base and the pipetting tubes movable lengthwise of the base.

Preferably the pipetting tubes are made of polytetrafluoroethylene asthis substance is hydrophobic and there is little tendency for aqueousliquids to be retained on its surfaces and be carried from onereceptacle to another during use and thus spoil the accuracy of theapparatus.

The invention will now be described in more detail, by way of examples,with reference to the accompanying drawings, in which:

FIGURE 1 shows, in side elevation, one form of apparatus;

FIGURES 2A, 2B and 2C are side elevations respectively of the frontportion, intermediate portion, and rear portion of the apparatus ofFIGURE 1 on an enlarged scale;

FIGURES 3A, 3B and 3C are respectively plan views of the three portionsof the apparatus shown in FIG- URES 2A, 2B and 2C;

FIGURE 4 is a greatly simplified perspective view of an alternative formof multiple pipetting apparatus;

FIGURE 5 is a view corresponding to FIGURE 4 but with sections brokenaway to expose the interior of the apparatus and in particular a pulleysystem used to raise and lower a line of pipetting tubes;

FIGURE 6A is a perspective view, with parts broken away of a trayforming part of a support used in the apparatus of FIGURE 4;

FIGURE 6B is a perspective view with parts broken away of a carriagealso forming part of the support;

FIGURE 6C is a perspective view with parts broken away of a rail,clamping pieces and T-piece, which may be used on the rail which formspart of the support;

FIGURE 7 is a scrap view of the apparatus of FIG- URE 4 and shows ahandle and associated stops for limiting its movement;

FIGURE 8 shows schematically parts of the apparatus of FIGURE 4 andtheir interconnections;

FIGURE 9 illustrates a mechanism for drawing liquid into and expellingliquid from the pipetting tubes of FIGURE 4; and

FIGURE 10 is a sectional view of a mount used for supporting a pipettingtube in FIGURE 4; and

FIGURE 11 is an electrical circuit diagram.

The apparatus shown in FIGURES 1 to 3 is very suitable for serologicalwork and is capable of being loaded with samples of serum, each of whichis to be dispensed into a number of receptables in various predeterminedproportions of dilution as will be explained hereafter. Whilst theapparatus may be loaded with many samples, it can dispense 10 of themsimultaneously and in 4 complete cycles of operation can dispense allthe samples with which the apparatus is loaded.

Referring now to FIGURE 1 it will be seen that the apparatus essentiallycomprises a base, generally indicated by the reference numeral 10, acarriage, generally indicated by the reference numeral 11, and apipetting assembly, generally indicated by the reference numeral 12.

The base 10 is generally of channel cross-section, comprising a bottommember 13, and side walls 14, which extend beyond the bottom member 13at the front end of the apparatus. The carriage 11 essentially comprisesa rectilinear platform 15 which carries a number of rollers 16 on eachof its longitudinally extending sides. The rollers 16 engage rails 17provided on the upper edge of each of the side walls 14 of the baseportion 10, in such a manner that the carriage 11 may be freely movedlongitudinally over the base portion 10.

The carriage 11 provides a support for a multiplicity of removablereceptacles for liquid, which will now be described. An aluminum frame18 extends transversely over the rear end of the carriage 11, and isprovided with forty holes 19, each of which is adapted to locate a testtube 29 for a sample of liquid which is to be dispensed by theapparatus. The forty holes 19 are arranged in four columns of 10, eachof which extends transversely across the carriage 11. The frame 18 isfollowed by a frame 21, which is provided with forty holes 22 each ofwhich is adapted to locate a test tube 23. The holes 22 in the frame 21are arranged in a like manner to the holes 19 in the frame 18. The frame21 is followed by a rectangular bath 24 which extends transversely overthe entire width of the carriage. The bath 24 is intended to receivewaste material as will be explained in greater detail hereinafter. Thebath 24 is followed by a further bath 25 which likewise extendstransversely over the entire width of the carriage. The bath 25 isadapted to hold a diluent for the samples which are to be dispensed bythe apparatus. The bath 25 is followed by a plate 26, which is providedwith eighty blind holes 27, each of which forms a receptacle for liquid.The eighty holes 27 are arranged in eight colums of ten, each of whichextends transversely over the width of the carriage. The plate 26 isfollowed by a plate 28 which is provided with eighty blind holes 29arranged in a like manner to the holes 27 in the plate 26.

The pipetting assembly 12 essentially comprises an L-shaped memberhaving one limb formed by a tubular arm 39 pivotally mounted at itslower end to one of the side Walls 14 of the base portion 10. The arm 30carries at its upper end a bar 31 forming the other limb of the L andextends transversely over the upper face of the carriage 11. The bar 31supports ten pipetting tubes 32 which extend therefrom in spacedparallel relationship downwardly towards the upperface of the carriage11.

The tubes 32 are formed from a polytetrafluoroethylene' material. Eachpipetting tube 32 is connected to a pipe or tube 33 which extends fromits upper end through the arm 30 and an aperture 34 in one of the sidewalls 14 of the base 10 to the interior of the channel-section of thebase. Each tube 33 is connected to one of a set of syringes 35 disposedbetween the side walls 14 of the base. The ten syringes 35 extendlongitudinally of the apparatus and are arranged in parallel spacedrelationship in a line which extends transversely across the apparatus.The plungers 36 of the syringes 35 are all connected rigidly to a barelement 37 which is in turn connected to a toothed rack 38 at each ofits ends. An axle 39 extends transversely of the apparatus and iscarried in bearings mounted in each of the side walls 14. The axle 39carries pinions 40 which are in engagement with the racks 38. One end ofthe axle 39 carries a radially directed handle 41 which is provided withreleasable locking means 42 adapted to co-operate with a plurality ofstops 43 mounted on an arcuate guide frame 44. Rotation of the handle 41causes actuation of the plungers of the syringes 35 by means of thepinion-s 40, racks 38 and bar 37.

A device in the form of a handle 45 is provided for controlling theraising and lowering of the pipetting tubes 32 and also the longitudinalposition of the carriage 11 on the base 10, in a manner which will nowbe described.

The handle 45 is rigidly secured to one end of an axle 46 which extendstransversely of the carriage at a position adjacent the front endthereof. A short arm 47 is firmly secured to the axle 46 and projectsdownwardly therefrom, its lower end being connected with the undersideof the carriage 11 by a tension spring 48. The arm 47 carries a freelyrotatable pulley 49 around which passes a wire or cord 50. One side ofthe cord 56 extends backwardly from the pulley 49 to a further pulley51. freely and rotatably mounted at the rear end of the carriage 11. Thecord passes round the pulley 51 and forwardly to a position beneath thepipetting tubes 32 where it is firmly secured to a bracket 52. The otherside of the cord 50 extends rearwardly from the pulley 49 to a pulley 53mounted on one of the side walls 14. The cord 50 passes round the pulley53 and through a small aperture 54 in the side wall and round a furtherpulley 55 freely mounted on the outside of the side wall 14, whence itextends to the end of a lever 56 connected with the arm 30 at theposition where the latter ispivoted t the wall 14.

The side of the platform 15 constituting the carriage 11 adjacent thearm 30 is provided with a side wall 57, whose upper edge defines a camsurface 58 provided with a slot or notch 59 transversely opposite eachtransversely extending row of receptacles 20, 23, 24, 25, 27 or 28. Arod 60 is pivotally connected to the lever 56 by its rear end, and ispivotally connected to a bell crank lever consisting of arms 61 and 62at its front end. The upper end of the arm 61 carries an interlock pinor peg 63 which is adapted to rest either on the cam surface 58 providedby the wall 57 or in one of the slots or notches 59.

When the handle 45 is rotated, the cord 50 moves in such a manner as tooperate on the lever 56 as to pull same forwardly and cause the arms 30and 61 to rise, whereby the lower ends of the pipetting tubes 32 areremoved to a position wherein they are spaced from the receptaclessupported by the carriage 11, and whereby the pin 63 is moved to aposition wherein it disengages with the notches 59 and the cam surface58. When the arms 30 and 61 are in their raised position, the handle 45may be used to pull the carriage forwardly or to push same rearwardly.The carriage may be halted in any desired position and the handle 45released so as to allow the arms 30 and 61 to fall. It will beappreciated that the arm 30 can only assume its lowermost position whenthe peg 63 can engage one of the notches 59, and the latter are arrangedso that the arm 30 can only be lowered completely when the carriage isin such a position that the pipetting tubes 32 will engage onetransversely extending column of the receptacles carried by the carriage11. The cam surface 58 and pin 63 provide interlocking means designed toensure that the carriage cannot be moved along until such time as thepipetting tubes 32 are in a sufficiently raised position to ensure thefree passage of the receptacles beneath the lower end of same.

The apparatus may be used in a variety of different ways, but oneparticular way will now be described. Initially, the forty tubes 20 arefilled with forty different samples of serum which it is desired todispense, the receptacles 23, 24, 27 and 29 being empty, and thereceptacle 25 being filled with a diluent. The handle 41 is operated toensure that the plungers 36 are fully depressed into the syringes 35,and the carriage 11 is aligned so that the rearrnost column of the tubes20 is aligned beneath the pipetting tubes 32, which are then lowered sothat they penetrate the samples of serum contained in these tubes. Thehandle 41 is operated to draw off a known volume of serum from each ofthe ten tubes 20 in the rearrnost column thereof into the ten pipettingtubes 32. The carriage 11 is then moved backwardly until the rearrnostcolumn of the tubes 23 are aligned beneath the pipetting tubes, 32 whichare then lowered so as to penetrate same. The handle 41 is then operatedto discharge a known volume of the serum from each of the pipettingtubes 32 into their respective tubes 23. The carriage is again movedbackwards, and the pipetting tubes lowered into the receptacle 25 whenthe handle 41 is operated to draw off a known volume of the diluent intoeach pipetting tube 32. The carriage is again moved backwardly until thepipetting tubes are aligned with the rearrnost column of holes 27 whenthe tubes 32 are again lowered to engage such holes. The handle 41 isoperated to discharge all the fluid from the pipetting tubes 32 into theholes 27 to ensure mixing of the serum with the.

diluent. The handle 41 is then operated to draw ofl a known volume ofthe serum from each of the holes 27 into the tubes 32 leaving apredetermined volume therein. The carriage is again moved backward untilthe tubes 32 are aligned over the next column of holes 27, whereupon thetubes 32 are lowered, and the handle 41 operated to discharge a knownvolume of the serum into each of the holes 27. This last operation isrepeated twice in the two following columns of holes 27, whereupon thecarriage is moved forwardly to bring the receptacle 24 for waste beneaththe pipetting tubes 32, which are lowered thereinto and the handle 41operated to discharge any remaining serum and diluent from the pipettingtubes 32 into the receptacle 24. The entire cycle of operations thus fardescribed is then repeated for each of the three remaining columns oftubes 20 containing samples of serum, in each case, the :carriage beingmoved to align the tubes 32 with the desired receptacles at each stageof the cycle.

The stops 43 on the guide 44 for the handle 41 may be arranged atpredetermined positions to facilitate the operation of the handle 41 todraw up and discharge the desired and predetermined volumes of fluid ateach stage of the operation cycle.

It will be appreciated that the apparatus can be used to dispense fortysamples of serum each into a plurality of receptacles at known volumesand known dilutions in a very short time, both on account of the factthat ten samples may be dispensed simultaneously and also on account ofthe simple operations required to effect the dispensing.

A second example of multiple pipetting apparatus in accordance with theinvention is shown in FIGURE4. The apparatus comprises a base on which asupport 101 is slidably mounted by means of runners 102 fixed to thebase. A tower 103 extends upwards behind the support 1431 alongside acasing 104 containing electrical control apparatus to be describedlater. The front of the casing 104 is fitted with a timer 105 andvarious control knobs 106 and indicating lights 109.

The tower is [provided with an upper rectangular slot 167 through whichextends an angle member 108 detachably mounted on a bracket 99. Thehorizontal web of I rests on the top surface of the the angle member isformed with a slot 110 extending above the support 101 and in which areslidable mounts 111 each supporting a pipetting tube 112. Although onlyfour pipetting tubes are shown more may be mounted in the slot 110 asrequired. Pipes 113 pass from the tops of the mounts 111 along themember 108 and through the slot 107 into the tower 103. A second slot114 is spaced directly beneath the slot 107 and a vertically movableinterlocking pin 115 serving for indexing the support 101 projectsthrough the slot 114 so that its end overlies the top surface of a rail116 fixed to the support and extending in the direction of its movement.Locating pieces 117 of which only five are shown, are movable todifferent positions along the top flanges of the rail 116. ,When the pin115 is in the top of the slot 114 the locating pieces pass beneath thepin when the support 101 is moved along the base 100. When the pin 115is in the lower position shown, it is spaced close to the top surface ofthe rail 116. Whether or not the pin 115 is allowed to assume theposition shown, depends on the positions of the pieces 117. If thepieces 117 on the side nearest the pin are closely spaced so as toprovide a continuous top surface the pin 115 will be prevented fromassuming its lower position. However, if the pieces 117 are spacedsufficiently to provide a slot between them into which the pin 115 canfit then it will enter the slot and will assume the position shown. Thelength of the pin 115 is such that it can be stopped from entering aslot by the pieoes on both sides of the rail 116. Thus the clampingpieces 117 on one side of the rail can be used to form one side of eachof a series of transverse slots and the precise positions of the othersides of the slots formed from further locating pieces mounted on theother side of the rail and overlapping those on the first side where afraction of a width of a locating piece is required.

The support 101 comprises a carriage 118 of inverted channel shape withthe runners 102 being fitted to the inside faces of the downturnedflanges of the carriage. FIGURE 6B shows the carriage in more detailfrom which it will be seen to have a pair of end flanges 120 and acamming surface 121 formed on the outside of one downturned flange. Inits top surface the carriage is pro vided with .two locating holes 122for accommodating studs 123 projecting downwards from the underside of atray 124 shown in more detail in FIGURE 6A which carriage 118 as shownin FIGURE 4. The tray 124 is provided with parallel upstanding sideflanges 125 each of which serves as a guideway for opposite ends of aU-channel partition 126 which is movable to different positions alongthe tray 124. At its ends each of the partitions 126 is provided with aclamp 127 which may be tightened to lock the partition in a desiredposition. The partition is of channel shape and clamp blocks 128 areslidable to different positions along opposite sides of the channel.There is sufiicient spacing between the clamp blocks on opposite sidesof the partition to enable them to be slid past one another withoutobstruction.

Referring again .110 FIGURE 4 the support 101 is provided with fixturesinto which a programme card 130 can be fitted in order to suit aparticular sequence of operation to be carried out. A pointer 131 on thebase indicates the particular point in the programme at any instant anda hand lever 132 close to one end of the support 101 enables the supportto be moved along the base 100 to difiiereut positions in accordancewith the programme 130. The handle 132 is also rotatable to raise andlower the pipetting tubes 112 as will be described later.

The base 100 is provided with a handle 133 shown in more detail inFIGURES 7 and 9. The handle is movable to diiferent angular positionsdetermined by adjustable stops 134 set to positions corresponding tovolumes of liquids to be drawn into or expelled from the pipetting tubes112. Each of the stops 134 is mounted on an armate frame 135 concentricwith the axis of the handle 133, and one or both sides 136 of each stop134 is planar to provide an abutment for the handle 133. An overriderbutton 137 is fixed in the top of the handle and is fixed to a peg 139which cooperates with the abutment surfaces 136 when the button is notpressed. Where no planar abutment surface 136 is permitted the peg 139is able to ride over the curved undersurface of the stop 134. However ifthe button 137 is pressed the peg 138 is also able to move past theabutment surfaces 136 so that the handle 133 is able to be moved todifferent positions past the stop. The button 137 acts against a spring140 mounted inside the handle 133.

Turning to FIGURE 5, the top of the tower 103 provides a stand on whicha reservoir bottle 141 may be placed. Piping 185 extends from the bottlethrough the tower to a wash trough 142 mounted in the base 100 directlybeneath the number 108. When the wash trough is not in use the support101 is able to pass freely over it.

The length of the wash trough is the same as the length of the slot 110in the member 108 and is shown in more detail in FIGURE 8. It comprisesa rectangular trough divided by a horizontal plate 143 into an uppercompartment 144 and a lower compartment 145. A slot 146 slightly widerthan the cross-sections of the lower endportions of the pipetting tubes112, is formed in the plate 143 directly beneath the pipetting tubes anda removable sloping glass plate 147 slopes into the upper compartment144 and terminates above the slot 146. An electrically operatedimmersion heater 148 provided with a thermal cut-out is mounted in lowercompartment and a liquid inlet pipe 150 opens through the bottom of thecompartment 145. A liquid outlet pipe 151 opens into the top compartment144 through the plate 143 and extends downwards through the floor of thebottom cornpartment 145.

FIGURE 5 shows the method of raising and lowering the member 108 onwhich the pipetting tubes 112 are mounted. The bracket 99 supporting themember 108 is mounted inside the tower 103 on a telescopic guidewayhaving a lower part 161 which is fixed inside the tower and an upperpart 162 which is vertically slidable along the lower part. The bracket99 is fixed to the upper part 162 and a cross brace 163 extendshorizontally away from the member 108 and is provided at its endportionwith a hole 164 which is a sliding fit along a slide rod 165 fixed atits upper and lower ends inside the tower. The cross brace 163 preventsundesirable horizontal movement of the member 108 about the guideway160.

The weight of the member 168 is carried by a wire 166 which extendsaround a first pulley 167 in the upper end portion of the tower andaround a deflector pulley 169 which is movable horizontally to vary theeffective length of the wire 166. A tensator spring 79 in the top of thetower and attached .to the sliding part 162 counter-balances much of theweight of the pipetting tubes. The other end of the wire 166 is fixed tothe periphery of a second pulley 168 mounted on a shaft 170 journalledinto the tower between the slots 107 and 114. A third pulley 171 is alsofixed to the shaft 170 and a second wire 172 is fixed to the peripheryof the third pulley 171. The second wire 172 extends around an idlerpulley 173 which maintains it in tension and around a stationary mountedpulley 174 fixed in the base 100 at one end. The other end portion ofthe wire 172 extends through a tensioner 175, which is rotated by thehand lever 132 fixed to the carriage 118, to an anchorage 177 at theother end of the base 100. A helical spring 180 ensures the engagementof the tensioner with the wire 172.

A hanging link 181 is pivoted at its upper end to the third pulley 171eccentrically with respect to its axis and carries the interlocking pin115 at its lower end.

The first pulley 167 is fixed to one end of a lever 182 which is biasedupwardly by a coil spring 183 against an adjustable stop. The lever ispivoted at 104 and is positionally controlled by a wire 186 whichextends downwards through the tower- 103 and is anchored at its lowerend to a cam rider 137 mounted at the free end of a spring loaded lever188 as shown in FIGURE 8. The earn rider 187 is positioned in the pathof movement of the cam surface 121 provided on the side of the carriage118 as shown in FIGURE 6B. The camming surface 121 is so positioned thatit engages the cam rider 107 to press it downwards when the support 101is so far to the right of FIGURE 4 that is is not interposed between thepipetting tubes 112 and the wash trough 142.

The supply of liquid to the wash trough 142 is controlled by a solenoidoperated valve 101 mounted in the top of the tower 103 beneath thereservoir bottle 141. Operation of the valve 191 is controlled by anelectrical circuit shown in FIGURE 11 and described in detail later. Theelectrical circuit also controls operation of the immersion heater 148in the wash trough 142, the in dieating lamps 107 in the casing and anair pump 149.

The pipes 113 from the mounts 111 extend through the slots 107 in thetower 103 and downwardly to a set of syringes 200 mounted in a lineacross the base 100 and shown in FIGURE 9. There is one syringe 200provided for each of the pipetting tubes 112 and their plungers are heldby fixtures 201 to a cross element 202 which is fixed at its ends to apair of racks 203. The racks are engaged by pinions 204 fixed to an axle205 extending through the side of the base and on which the handle 133,is mounted. The cylinders of the syringes 200 are provided close totheir rear ends with branch pipes 207 opening into a manifold 208 whichextends into a flask 210 containing a drying agent, such as silica gel,and a bacteriological filter. The flask 210 is mounted in the foot ofthe tower 103 and is accessible through a door (not shown) at the backof the tower. A pipe 211 extends through the back of the tower to theair pump 149 (see FIGURE 11) for driving air into the drying flask 210.The branch pipes 207 open into the cylinders of the syringes atpositions which enable them to discharge dried air through the syringes200 and the pipes 113 when the plungers are in their rearmost positionswith respect to the syringes 200. At this position, which is indicatedby one of the stops 134 associated with the handle 133, a microswitch190 is operated.

FIGURE shows one of the mounts 111. This comprises -a bush 220 flangedat 222 and having its upper portion threaded and passing through theslot 110 where it is clamped into position by a lock nut 221 whichclamps the member 108 to the flange 222. An elbow tube 223 is held in asocket at the upper end of the sleeve 220 by a cap nut 224 and a packingring 225. The other end of the elbow passes into the end of the pipe 113which is conveniently made of polyethene tubing. The pipetting tube 112is made of polytetrafluoroethylene and its upper end is a force fit on aspigot formed in the underside of the mount 111. A stainless steelsleeve 226 closely surrounds the junction of the pipetting tube 112 withthe mount 111 and prevents undue flexing of the pipetting tube at thispoint and assists their alignment.

FIGURE 6C shows the rail 116 in more detail and also illustrates the useof a T-piece 230 to bridge between 10- cating pieces 117 when a slot isnot to be formed between the clamping pieces over a relatively largedistance.

The T-piece 230 is gripped between the locating pieces 117a, 1171) and1170, to prevent lowering the pin 115, and slots for reception of thepin are formed between the pairs of clamping pieces 1172, 117 at eachend of the T-piece. The locating pieces 117 are provided in differentsizes to suit different lengths of receptacles 230 into which pipettin gis to be carried out.

Referring again to FIGURE 4 the receptacles 230 into which liquid is tobe pipetted are mounted in a test tube rack 231 of standard size.Although only one such rack is shown in FIGURE 4 it is to be understoodthat several such racks, arranged side by side, would normally be usedand they are standard items of laboratory equipment. The racks 231 maycome in several difierent sizes according to the purpose for which theyare intended and the number of receptacles which are to be carried. Forclarity a rack having two columns of eight openings and containing fourtest tubes 230 has been shown, the rack extending entirely across theWidth of the tray 124. However dilferent sizes of rack may be ofdifferent lengths but can nevertheless be firmly clamped in position onthe tray by the partitions 126 as is described below.

FIGURE 11 shows the electrical wash control circuit for the apparatus.It comprises a main ON/OFF switch 29 which closes to complete electricalcircuits to a number of cam operated contacts CCI, CC2, CC3, CC4 andC05. The cams controlling the contacts are driven in unison by the timerand are so arranged that the washing sequence is completed in onecomplete revolution of the timer 105. During one complete revolution of360 the contacts CO1 and CC2 are closed between 1' and 201; the contactCC3 is closed between 340 and 20; the contact CO4 is close-d between 0and 200; and, the contact CCS is closed at 360.

The contact CC2 is a change-over contact and selectively controlsoperation of the pump 149 and the heater 148. During the arc l-201 theheater 148 is energised and during the arc 201-1 the pump 149 isenergised. The electrical supply to the timer 105 and the contact CC2 iscontrolled by a manually operable switch 189 which, when opened, allowsthe pipetting tubes to be washed out with cold water, but which isclosed it the washing sequence employing the timer 105 is to be used.Various lamps 109a-d are used to signify different stages in the washingsequence. The contact CC4 is also a change-over contact and is in theposition shown during the 0-200.

A change-over contact 179' controls the supply to the manual switch 189,the contact 179' being operated by a microswitch 179 in the tower 103 asshown in FIGURE 5. The microswitch 179 is so arranged that the contact179' is in the position shown in FIGURE 11 if the pipetting tubes 112are lowered sufficiently for their tips to reach the surface of theliquidin the wash trough 142. If the pipetting tubes are above thispoint the contact 179' assumes its lower position. Operation of themicroswitch 179 is carried out by its engagement with the movable part162 of the slideway 160 during lowering of the pipetting tubes 112.

To prepare the apparatus for use the operator places the test tube racks231 which are required onto the tray 124.

Each of the test tube racks is held in place by two partitions 126 whichare moved against opposite sides of the rack. The partitions 126 areonly able to move parallel to themselves so that they ensure, byengaging the sides of the racks 231, that the columns of receptacles 230extend parallel to the line of pipetting tubes 112. The spacing betweenthe pipetting tubes 112 is arranged to be the same as that between thereceptacles of each column and the test tube racks 231 are clamped inthe position at which the pipetting tubes engage with the receptacles,by adjustment of the clamping blocks 128, which are then tightened. Thelocating pieces 117 are then positioned to ensure that the interlockingpin 115 can pass between two adjacent pieces 117 when the pipettingtubes 112 rest centrally in each row of receptacles. The columns ofreceptacles are next brought into exact agreement with the programmecard and to do this the pipetting tubes 112 are raised and each columnis brought beneath the row of pipetting tubes 112 which are then loweredby means of the hand-lever 132 into respective receptacles 230 of acolumn. The programme card 130 is then marked 3 at the point indicatedby the pointer 131. When this has been done two of the locating pieces117 on opposite sides of the rail 116 are then locked in position.

When all of the test tube racks or similar such devices which may beused for different for-ms of receptacles are clamped into their correctpositions and the programme card 130 completed the bottle 141 is placedon top of the tower 103 and connected to the piping 18S extending to thewash trough 142. Also, the stops 134 are placed at different positionsalong the path of movement of the handle 133 according to volumes ofliquids it is required to draw into and expel from the pipetting tubes112. The positions of the stops 134 are signified by a calibrated scale(not shown) extending around the path of movement of the handle 133. Theapparatus is now ready for use.

To use the apparatus the hand lever 132 is rotated counter-clockwise toraise the line of pipetting tubes so that their lower ends are liftedclear of the tops of the receptacles 230. The action of rotating thehand lever 132 tensions the wire 172 and causes the pulley 171 to rotatein a clockwise direction as will be clear from FIG- URE 5. This rotationis transmitted through the shaft 170 to the second pulley 168 so thatthe wire 166 is drawn around the top pulley 167 and pulls the member 108upwards. This upward movement is permitted by the telescopic guideway160 and any tendency for the line of pipetting tubes to twist isresisted by the engagement of the cross-brace 163 with the slide rod165. During rotation of the said pulley 171 the hanging link 181 is alsodrawn upwardly so that the interlocking pin 115 is lifted clear of theclamping pieces 117 or T-pieces arranged along the rail 116. The heightof the locating pieces 117 selected is such that the interlocking pin115 does not clear the slot formed between them until the lower ends ofthe pipetting tubes 112 are clear of the tops of the receptacles 230.

The support 101 is now displaced by the hand lever 132 along the base100 to the first position indicated by the pointer 131 on the programmecard 130. At this pOSitiO)? the handle 132 is allowed to rotate in aclockwise direction. If the pipetting tubes 112 are not correctlyaligned with a column of receptacles the interlocking pin 115 will notenter the corresponding slot formed between the clamping pieces 117 butwill engage the top surface of one or either of the clamping pieces.This prevents further rotation of the third pulley 171 so that furtherlowering of the member 108 is prevented before the pipetting tubes 112reach the level of the tops of the receptacles 230.

Assuming the apparatus has been set up correctly the interlocking pin115 passes between the clamping pieces 117 defining the slot associatedwith the first position and allows the lower ends of the pipetting tubesto be lowered into the column of receptacles. When the pipetting tubesare in their lower positions. their weight is carried by the wires 166and 172 and the interlock pin 115 is just clear of the top surface ofthe rail 116.

The operator draws the desired volumes of liquids into the pipettingtubes 112 'by rotation of the syringe-operating handle 133 up to a stop134 as shown in FIGURE 9. The hand lever 132 is then rotated in thereverse direction to raise the pipetting tubes and after they are liftedclear of the receptacles 230 the interlocking pin 115 allows the supportto be moved to the next position indicated by the programme card 130. Itwill be appreciated that the engagement of the interlocking pin 115 inthe slot formed between the clamping pieces 117 ensures that the support101 cannot be moved as long as the pipetting tubes are engaged in thereceptacles 230.

At the next position the procedure is repeated and perhaps a secondliquid is drawn into the pipetting tubes.

At a third position denoted by the programme card it may be required tomix the two liquids contained in the pipetting tubes, in a column ofreceptacles. To accomplish this the pipetting tubes 112 are lowered intorespective recepetacles 230 of the column, as described above, and thehandle 133 is moved in the reverse direction. This expels the liquidfrom the pipetting tube into the column of receptacles. To mix theliquid in the receptacles thoroughly the handle 133 may be workedbackwards and forwards a few times. Samples of the mixed liquid may thenbe transferred by the pipetting tubes 112 to other columns ofreceptacles as required.

Between different programmes, or at periods during a single programme itmay be required to clean the pipetting tubes thoroughly. This may becarried out either by a cold wash, in which case the manual switch 189'is opened, or by a hot wash, in which case the manual switch 189 isclosed.

The procedure for cold washing will first be described.

The manual switch 189' is opened and the support 101 is moved as far asthe right of FIGURE 4 as possible so that the camrning surface 121 ofFIGURE 5 forces the cam rider 187 downwards. This draws wire 186downwards also so that the pulley 167 in the top of the tower 103 ispulled downwards against the spring 183. This lowers the line ofpipetting tubes 112 from their upper positions by twice the downwardmovement of the pulley 167.

The hand lever 132 is then rotated to lower the line of pipetting tubes112 and, as a result of the upper pulley 167 being lowered, the lowerends of the pipetting tubes are able to descend below the level of thesupport 101 and into the slot 146 of the wash trough 142.

When the tips of the pipetting tubes reach the top of the wash trough142 the descending upper part 162 of the slideway 160 operates themicroswitch 179 so that its changeover contact 179' moves to theposition shown in FIGURE 11. At this time the contact CC4 is in theposition shown so that the solenoid-operated valve 191 is energised byway of the closed contact CO3 and opens to allow wash liquid to flowfrom the reservoir 141 into the bottom compartment 145' of the washtrough 142. The liquid from the lower compartment 145 flows upwards pastthe lower end portions of the pipetting tubes 112 with a millrace effectso that the end portions are thoroughly cleaned by the continuouslyflowing hot liquid. At the end of the washing time the operator turnsthe hand lever 132 to lift the pipetting tubes 112 a small amount sothat their tips are drawn out of the slot 146. and rest against the topsurface of the sloping glass plate 147. Glass is hydrophilic whereas thepolytetrafluoroethylene of the pipetting tubes is hydrophobic so thatany drops of water on the tips of the pipetting tubes are transferred tothe glass plate 147. This reduces the risk of dilution of the nextliquid into which the pipetting tubes are dipped by water adhering tothe outside of the pipetting tubes from the wash trough 142.

The hand lever 132 is fully rotated counterclockwise to raise thepipetting tubes 112 to their original positions.

As a result the microswitch 179 returns to its original state and itscontact 179' breaks the electrical circuit to the valve 191. Valve 191is de-energised and closes to stop the flow of wash liquid into the washtrough 142'. Throughout the washing the timer remains unenergised andthe contact CCS is closed to light the lamp 109d.

In certain circumstances it is necessary to thoroughly clean and dry theend-portions of the pipetting tubes 112 and for this purpose the hotwash, which is time sequenced by the timer 105, is necessary.

To use the hot wash the switch 189' is closed and the lower end-portionsof the pipetting tubes 112 are lowered into the wash trough 142 inexactly the same way as described above. However in this case operationof the microswitch 179 energises the timer 105 as well as the solenoid.The cams driven by the timer 105 are rotated and almost immediately thecontacts CC1, CCZ, and CO are operated as they all respond to 1 ofrotation. The contact CCZ changes over to energise the immersion heater148 and the contact CC1 lights the lamps 1ti9'a to signify operation ofthe heater. Should the reservoir bottle 141 inadvertently be empty,over-heating of the immersion heater is prevented by a thermal cut out148 so that excessive heating of the lower end-portions of the pipettingtubes is prevented.

The contact CC3 remains closed until the cams have rotated through 20during which time the end-portions of the pipetting tubes are washed incold water. After 20 of cam rotation contact 0C3 de-energises the valve191 which interrupts the supply of wash liquid from the bottle 141. As aresult the liquid in the trough 142 is raised to its boilingtemperature. The wattage of the immersion heater 148 and time taken forthe cams to rotate through 180 are so selected that the wash liquid,which may be water, is just brought to its boiling point and held therewhile the pi-petting tubes may be worked up and down by the handle 132to rinse thoroughly. The temperature of the wash liquid is sufiicientlyhigh to kill vegetative micro-organisms which might be present and thetime taken for the cams to rotate to 200 is sufficient for this purpose.

At 200 the contact CC4 changes over to break the electrical supply tothe timer 105 and energises a lamp 1090. This indicates that the rinsingsequence is completed.

When the operator observes light 1090 he lifts the pipetting tubes bythe hand-lever 132 to their upper position after allowing their tips torest momentarily on the glass plate 147, and this causes microswitch 179to operate and contact 179 to change-over.

If at this stage the plungers of the syringes 2% are not wound back totheir furthest extents the microswitch 199 will not be operated and theelectrical circuit to the timer 105 will be broken. To complete thiscircuit the operator winds back the plungers until he reaches a stop134. He will then see the lamp 111% light to indicate that the timer isagain operating and therefore the microswitch 199 has been closed.Simultaneously with the timer 105 operating the valve 191 is opened toallow cold water from the bottle 141 to flush out the hot rinse liquidfrom the trough 142.

A second or so later after operation of the timer the cams are rotatedto 201 and the contacts CCZ and CC1 operate to transfer the electricalsupply from the immersion heater to the pump 149 and to signify thatthis has taken place.

The pump 149 drives dry air from the flask 21% through the syringes201), this being permitted by the withdrawn plungers, and through thepiping 113 no the pipetting tubes 112 The dry air absorbs any moistureremaining inside the tubes 112 and this is facilitated by the tubes 112still being Warm from the previous rinsing operation. The pump continuesto run until the cams have rotated through the remainder of the 360 whencam contact CC4 again changes over to break the electrical circuit tothe timer 105. At 360 cam CCS also closes to indicate the cams havecompleted the entire sequence and the circuit is ready to start a freshsequence when desired.

During operation of the pump 149 the cam pass the 340 position at whichthe contact CC3 is once again closed to open the valve 191 and allowcold liquid from the bottle 141 to flush the hot contaminated rinseliquid from the trough 142. At the end of the washing and dryingsequence the support 101 is returned to its original position shown inFIGURE 4 so that the cam surface 121 no longer bears against the camrider 187. The spring 183 returns the pulley 157 to its topmost positionto lift the pi petting tubes 112 to their upper positions in readinessfor the next sampling operation.

Although the operation of the immersion heater 148, pump 14%, and timerhas been described in a sequence controlled circuit it will beunderstood that each may be provided with its own over-riding switch toenable it to be switched on and off independently if desired.

It will be appreciated that it is not intended to limit the scope of theinvention to the above examples only, many variations, such as mightreadily occur to one skilled in the art, being possible, withoutdeparting from the principles of the invention.

Thus, for example, the mechanical construction of the apparatus may bevaried in any number of ways without departing from the principles ofoperation. For example, in place of the solenoid valve shown in FIG- URE8 the control of wash liquid from the flask 141 maybe carried out bymechanically pinching the piping extending from the flask 141 to thewash trough. Such pinching may be carried out by sandwiching the pipingbetween a portion of the lever 182 so that the pinch is relieved whenthe pulley 167 is drawn downwardly by the wire 1%.

The pipetting arrangements may be different and the pipetting tubes neednot be formed from polytetrafluoroethylene though this material ispreferred, since as there is no tendency for liquids to wet the surfacesof such tubes very accurate quantities of fluid can be dispensed.

The apparatus may be used in any desired manner to effect any knownmethod of dispensing serological or other fluid samples for analysis.Thus the carriage may support receptacles for reagents of various kindsfor mixing with the samples under test, or receptacles for rinsing mediafor the pipetting tubes between any desired stages or cycles ofoperation.

The apparatus of the invention is able to dispense liquids with accuracyand at great speed.

As an example of the speed of use of the first apparatus describedabove, it was used by a skilled operator to prepare serial dilutions of1 in 8, 1 in 16, 1 in 32 etc. The sequences necessary took approximately2 /2 minutes, 1% minutes and 1% minutes respectively whereas to do thejob manually a skilled operator took 20 minutes, 10 minutes and 10minutes respectively. The accuracy of measurement was superior to thatattainable by manual methods and in general, in serological work, thespeed of use is between 5 and 10 times faster than with conventionalmethods. In another example using routine procedures which requiredeight measurements for each specimen, a single technician has, by usingthe apparatus of FIGURES 1 to 3, been able without difficulty or fatigueto dispense 500 specimens in an hour. Were conventional manual methodsto be used it would require two technicians each working three hours todispense 500 specimens.

I claim:

1. Multiple pipetting apparatus comprising a base, a support on the basefor holding receptacles disposed in rows and columns extending along andacross the support respectively, a member extending across the supportabove the level of the receptacles, a mechanism for producing relativelongitudinal movement between the support and the member, a line ofpipetting tubes mounted on the member above the level of respective rowsof receptacles, a set of syringes, pipes individually connecting thesyringes to the pipetting tubes, an element for operating the syringesin synchronism, a device for simultaneously raising and lowering thepipetting tubes when their lower ends are aligned with a column ofreceptacles, said support including a rectangular tray having slidablepartitions movable parallel to one pair of sides of the tray andcarrying adjustable clamping blocks movable parallel to the other pairof sides of the tray.

2. Apparatus as claimed in claim 1, in which the support is movable withrespect to the base.

3. Multiple pipetting apparatus comprising a base, a support mounted onsaid base for holding receptacles disposed in rows and columns extendingalong and across the support respectively, a tower extending upwardsfrom the base at one side of thesupport, an upright telescopic guidemounted inside the tower, a member extending horizontally away from theguide to an opening in the tower and extending across the support abovethe level of the receptacles, a mechanism for moving the support alongthe base, a line of pipetting tubes mount: ed on the member above thelevel of respective rows of receptacles, a set of syringes, pipesindividually connecting the syringes to the pipetting tubes, an elementfor operating the syringes in synchronism, a device for simultaneouslyraising and lowering the pipetting tubes when their lower ends arealigned with a column of receptacles, and interlock means for preventingoperation of the device until alignment of said lower ends.

4. Apparatus as claimed in claim 3, including inside the tower a sliderod extending parallel to the base, and a brace extending transverselyin a horizontal direction away from the member and slidable along theslide rod at its free end.

5. Multiple pipetting apparatus comprising a base, a support on saidbase for holding receptacles disposed in rows and columns extendingalong and across the support respectively, a member extending across thesupport above the level of the receptacles, a mechanism for producingrelative longitudinal movement between the support and the member, aline of pipetting tubes mounted in the member above the level ofrespective rows of receptacles, a set of syringes, pipes individuallyconnecting the syringes to the pipetting tubes, an element for operatingthe syringes in synchronism, a device for raising and lowering thepipetting tubes when their lower ends are aligned with a column ofreceptacles, means defining slots spaced along the support, an interlockpin vertically movable between two positions at one of which it engagesin a selected slot to prevent relative movement between the support andthe pipetting tubes and at the other of which it is spaced from the slotto allow such relative movement, and a linkage operatively connectedbetween the pin and the member so that they are moved in synchronism.

6. Apparatus as claimed in claim 5, in which the linkage includes a bellcrank lever.

7. Apparatus as claimed in claim 5, including a pulley in said linkageand rotated by said device, and a swinging link depending from saidpulley and having the interlock pin projecting from its lower endthrough a vertical slot confining movement of the pin to a verticaldirection.

8. Apparatus as claimed in claim 5, in which said means defining slotscomprise adjustable clamp blocks slidable to different positions along atrack extending along one side of the support.

9. Multiple pipetting apparatus comprising a base, a support on saidbase for holding receptacles disposed in rows and columns extendingalong and across the support respectively, a member extending across thesupport above the level of the receptacles, a mechanism for producingrelative longitudinal movement between the support and the member, aline of pipetting tubes mounted on the member above the level ofrespective rows of receptacles, a set of syringes, pipes individuallyconnecting the syringes to the pipetting tubes, a rack and pinion unit,a handle for rotating the pinion, an element movable with the racktowards and away from the syringes, fixtures connecting the plungers ofthe syringes to the element for operating the syringes in synchronism, adevice for raising and lowering the pipetting tubes when their lowerends are aligned with a column of receptacles, adjustable stops forco-operating with the handle to limit its movement, and an over-riderbutton on the handle for permitting it to ride over the stops whendesired.

10. Multiple pipetting apparatus comprising a base, a support on thebase for holding receptacles disposed in rows and columns extendingalong and across the support respectively, the member extending acrossthe support above the level of the receptacles, a mechanism forproducing relative longitudinal movement between the support and themember, a line of pipetting tubes mounted on the member above the levelof respective rows of receptacles, a set of syringes, pipes individuallyconnecting the syringes to the pipetting tubes, branch pipes extendingfrom the rear end portions of respective syringes to a common pipeconnection for supplying dried air severally to the syringes so that thedried air passes through the pipes and the pipetting tubes, an elementfor operating the syringes in synohronism, and a device for raising andlowering the pipetting tubes when their lower ends are aligned with acolumn of receptacles.

11. Apparatus as claimed in claim 10, further comprising a handle commonto said mechanism and to said device, said handle being movably mountedon said support and operable for producing said relative longitudinalmovement and for raising and lowering said pipetting tubes.

12. Multiple pipetting apparatus comprising a base, a support on thebase for holding receptacles disposed in rows and columns extendingalong and across the sup port respectively, a member extending acrossthe support above the level of the receptacles, a mechanism forproducing relative longitudinal movement between the support and themember, a line of pipetting tubes mounted on the member above the levelof respective rows of receptacles, a set of syringes, pipes individuallyconnecting the syringes to the pipetting tubes, an element for operatingthe syringes in synchronism, a device for raising and lowering thepipetting tubes when their lower ends are aligned with a column ofreceptacles, a wash chamber extending parallel to the columns, means forlowering the lower end portions of the pipetting tubes into the washchamber to clean them, means for circulating wash fluid past the endportions of the pipetting tubes when dipping into the wash chamber,means in said wash chamber defining upper and lower compartments and anelongated opening extending between said compartments and through whichsaid end portions of the pipetting tubes extend, an inlet for washliquid in said lower compartment, an outlet for wash liquid in saidupper compartment, an immersion heater in said lower compartment andterminating above one edge of said elongated opening.

13. Apparatus as claimed in claim 12, said wash liquid circulating meansincluding a reservoir mounted above the pipetting tubes, a pipeconnecting the reservoir to the liquid inlet of the lower compartment, avalve disposed in said pipe for controlling flow of wash liquidtherethrough, and means for operating said valve in unison with loweringmovement of the end portions of the pipetting tubes into the washchamber.

14. Multiple pipetting apparatus comprising a base, a support movable onsaid base and for holding receptacles disposed in rows and columnsextending along and across the support respectively, a member extendingacross the support above the level of the receptacles, a mechanism forproducing movement of the support along the base, a line of pipettingtubes mounted on the member above the level of respective rows ofreceptacles, a set of syringes, pipes individually connecting thesyringes to the pipetting tubes, an element for operating the syringesin synchronism, a device for raising and lowering the pipetting tubeswhen their lower ends are aligned with a column of receptacles,interlock means for preventing operation of the device until alignmentof said lower ends, a wash chamber mounted on the base be- 15 16 neaththe level of the support and extending parallel to References Cited thecolumns, means for lowering the lower end portions UNITED STATES PATENTSof the pipetting tubes into the wash chamber, means for circulating washfluid past the end portions of the 3 223 Hammond 2:3 pipetting tubeswhen in the wash chamber, cam means 5 g 8/1964 3: 22: -n-- ;-S-I:I--S--- 7 23 operated by said support when not lnterposed between3:188:181 6/1965 Peterson et a1. 73 425'4 the wash chamber and thepipetting tubes, and a safety element connecting the cam means to themember and r preventing said lowering means becoming operative untilLOUIS PRINCE Primal) Examme" operation of the cam means. 10 S. C.SWISHER, Assistant Examiner.

1. MULTIPLE PIPETTING APPARATUS COMPRISING A BASE, A SUPPORT ON THE BASEFOR HOLDING RECEPTACLES DISPOSED IN ROWS AND COLUMNS EXTENDING ALONG ANDACROSS THE SUPPORT RESPECTIVELY, A MEMBER EXTENDING ACROSS THE SUPPORTABOVE THE LEVEL OF THE RECEPTACLES, A MECHANISM FOR PRODUCING RELATIVELONGITUDINAL MOVEMENT BETWEEN THE SUPPORT AND THE MEMBER, A LINE OFPIPETTING TUBES MOUNTED ON THE MEMBER ABOVE THE LEVEL OF RESPECTIVE ROWSOF RECEPTACLES, A SET OF SYRINGES, PIPES INDIVIDUALLY CONNECTING THESYRINGES TO THE PIPETTING TUBES, AN ELEMENT FOR OPERATING THE SYRINGESIN SYNCHRONISM, A DEVICE FOR SIMULTANEOUSLY RAISING AND LOWERING THEPIPETTING TUBES WHEN THEIR LOWER ENDS ARE ALIGNED WITH A COLUMN OFRECEPTACLES, SAID SUPPORT INCLUDING A RECTANGULAR TRAY HAVING SLIDABLEPARTITIONS MOVABLE PARALLEL TO ONE PAIR OF SIDES OF THE TRAY ANDCARRYING ADJUSTABLE CLAMPING BLOCKS MOVABLE PARALLEL TO THE OTHER PAIROF SIDES OF THE TRAY.